POTATOES, ETC.] 



CHEMISTRY. 



347 



a sourish taste occasioned by lactic acid, produced by the 

 following process : The cabbage, which is cut into slices 

 and placed iu a barrel, intermingled with a certain 

 quantity of common salt, is pressed down, and in this 

 state it undergoes fermentation; lactic acid, together 

 with a small quantity of butyric acid, is thus produ 



The dissolving action of these acids for they act 

 also upon the fibrine of flesh is assisted by their 

 abundant proportion of compounds of chlorine and of 

 salt. In cabbage and asparagus, lettuce and cabbage 

 sprouts, potash considerably predominates ; in spinach, 

 soda and potash are nearly equal ; while in rhubarb, a 

 considerable amount of lime is contained. Cabbage 

 sprouts are remarkable for their amounts of lime and 

 magnesia ; and in the stalks and leaves of lettuce, in 

 asparagus and cauliflower, traces of manganese, a metal 

 very similar to iron, have been found. 



59. Digestibility of Vegetables. Are we, then, to 

 express surprise that those vegetables should be praised, 

 and put in comparison with meat, as aliments which 

 dilute the blood, when we know that their solid sub- 

 stance often forms scarcely one-tenth in weight of the 

 whole ; and, moreover, that it contains more salts than 

 albumen, without any undissolved albuminous substance 

 at all, but merely a small proportion of organic acid ? 

 A\ hiUt by themselves conveying very little nutriment to 

 Mood, as may be seen in the feeble muscles of the 

 inhabitants of the tropics, who live exclusively on herbs, 

 vegetables are of service, first in the digestive canal, by 

 dissolving the albuminous substances of the meat, and 

 afterwards in the blood itself, by keeping the album en 

 and fibrine in a liquefied state, but not as nutritious 

 food. 



The cellmose, which in several kinds of cabbage, espe- 

 cially in the stem, is present in a greater abundance, 

 belongs to an alimentary principle difficult of digestion ; 

 and tlds explains the flatulence wliich cabbages not un- 

 usually occasion in weak digestive organs. Of all other 

 kinds of cabbage, the white cabbage used for saurkrout 

 is remarkable for its amount of lactic acid, which renders 

 it a readily digestible aliment. This useful vegetable ia 

 sometimes charged with indigestibility a charge which 

 should be brought against the pork and hard-boiled 

 mashed peas so often taken with it. 



If it be, therefore, apparent that aa vegetables alone 

 furnish a very insufficient compensation for the excreted 

 substances, the fact that an exclusively vegetable diet 

 affords but a defective nutrition to the tissue, is at once 

 explained. Not only do the muscles become powerless, 

 but a smaller quantity of nutriment is convoyed to the 

 brain. Hence results an irresolute will, and a cowardly 

 relinquishment of independence, as illustrated iu the 

 timid and slavish Hindoos, and other inhabitants of the 

 tropics, who feed almost exclusively on vegetables. 



Since, moreover, the alimentary principle of vegetables 

 requires less oxygen than meat, bread, or the leguminous 

 seeds, for the production of the same quantity of car- 

 bonic acid and water; trhile, at the same time, the 

 amount of oxygen we inhale remains undiminished, it 

 becomes evident why we exhale more carbonic acid while 

 living on vegetables, than when supported by a more 

 invigorating diet of meat, bread, and leguminous seeds. 

 Precisely for this reason do we become satiated iu a 

 short time by an exclusively vegetable diet ; for the 

 blood and the tissues are only scantily supplied with 

 albumen. But these tissues, containing a scanty amount 

 of albumen, furnish fewer nitrogcnised products of de- 

 composition ; and the excretion of urea and uric acid is, 

 during the twenty-four hours, considerably diminished. 

 Amount of urine, however, is increased by the salts 

 and acids of the vegetables ; and everybody knows how 

 quickly the constituents of the asparagus, conveyed to 

 the blood, and attracted therefrom by the kidneys, 

 themselves to the sense of smelling in. the 



Jiy substituting vegetables which are poor in albumen, 

 fi.r one part of the meat we take as a meal, the supply 

 of ilbnminou bodies is diminished, and the digestion of 

 what wo have taken facilitated. Thus a combination is 



performed intermediate between meat and vegetables; 

 the blood contains more water than the meat, more 

 solid substance than the vegetables; and, by adding 

 together the amount of albuminous substances in the 

 meat and vegetables, and dividing the total into two 

 equal parts, the average quantity of albumen in the 

 composition may be found approximately corresponding 

 with that in the blood. Thus the seeming chance be- 

 comes an approved law ; and, instead of an arbitrary 

 taste being left to dictate the choice of aliments, the 

 necessity of attending to the law is apparent, clear 

 light being thus thrown upon the connection between 

 nutriment and blood ; and the night in which the 

 realms of knowledge were peopled with nebulous spec- 

 tres and conjectural dreams, tending to show that all 

 things existed for a settled purpose, is turned to day and 

 conviction by the discoveries of science. 



CO. Potatoes and Edible Hoots. Although in ordi- 

 nary life we class the potato and other edible roots in 

 the same category as the "vegetables," -we must not 

 forget that these roots and tubers considerably surpass 

 the latter in the quantity of solid substances which they 

 contain ; on an average, the proportion of water they 

 contain does not greatly exceed that of meat. 



Are, then, potatoes and edible roots to be compared 

 with meat in their nutritive qualities ? Here it appears 

 how important it is to compare the connection between 

 the several groups of alimentary principles represented 

 by the solid substances, with the composition of the 

 blood, if we would accurately estimate their nutritive 

 quality. By such comparison it will be found, that in 

 potatoes, turnips, carrots, beetroot, parsnips, and Jeru- 

 salem artichokes, in leeks and celery, shallots, onions, 

 and radishes, the constituents of fat surpass the albu- 

 men iu precisely that proportion in which the latter 

 ought to have exceeded tlio former, had these edible 

 roots been intended of themselves to sustain the com- 

 position of the blood ; thus the soluble albumen, wliich 

 alone represents the albuminous substances in these 

 roots, often constitutes less than the one-hundredth, and 

 sometimes only the two-hundredth parts in weight; while 

 the constituents of fat fluctuate between one-furth 

 and one-fifth. 



In the several roots and tubers, the constituents of fat 

 are very different in kind. Cellulose and gum are indeed 

 found in all of them ; but wliilo the potato is remarkal >!e 

 for its amount of starch, wo find in carrots, beetroot, 

 and Jerusalem artichokes, an abundance of sugar also. 



The roots just mentioned as abundant in sugar, and 

 also turnips, contain a new compound of carbon, hydro- 

 gen, and oxygon ; which contains more oxygen, in pro- 

 portion to its hydrogen, than the constituents of fat. 

 This substance, in the unripe fruit, thickens the walls of 

 the cells, consisting of cellular tissue, and is denominated 

 vegetable jelly or pectose. By boiling, it is transformed 

 into a gelatinous substance called pectic acid, which 

 might, therefore, be called gelatine acid. But since this 

 gelatine acid is not transmuted into sugar, either by our 

 digestive juices or by any artificial means, the vegetable 

 jelly and the gelatine acid cannot be classed with the 

 constituents of fat. 



Fat is contained in potatoes and carrots in very small 

 quantity ; while iu artichokes, besides fat, a trace of wax 

 has also been found. Bush-nuts contain, with a great 

 amount of starch, a considerable proportion of fatty oil. 

 The pungent taste of leeks and garlic, of radishes and 

 horse-radish, of onions and parsley root, is produced by 

 certain volatile oils ; for these oils, if extracted from the 

 roots, will be found to possess exactly the same peculiar 

 pungent smell and acid taste as the roots themselves. 

 The garlic oil, which exceeds all other oils in pungency 

 of taste and smell, is composed of carbon, hydrogen, and 

 sulphur, and is imperfectly soluble in water. 



Organic acids, which were mentioned as characteristic 

 of vegetables, are also to be found in these roots : thus 

 the malic acid in potatoes and carrots ; the citric acid, 

 composed of the same ingredients as the former ; and 

 tartario acid, containing a greater proportion of oxygen 

 than the former, are found in the Jerusalem artichoTce. 



